[pyoung]

A extremely simple analogy here would be home loans. If your home loan costs you ~4%, but you can make 10% in the stock market, than it would make no sense to pay off your home loan early, because you could use that money and invest in the stock market (a net of 6%).

I am no accountant, but in Tesla's case, it sounds like they now have a pile of money that they are going to sit on for emergencies, and that it may make sense for them to pay down this loan early with some of this cash because it reduces their liabilities (by reducing the interest they owe), whereas sitting on it nets a 0% (or near 0%) interest rate. Also, I wouldn't be surprised if there was some political/strategic motivation for paying off the loan. Unfortunately, Solyndra has become synonymous with the loan program, and I wouldn't be surprised if there is some pressure from investors or the board to distance Tesla from the program because of that.